Nine state lawmakers, including a few from the Bay Area, have signed a letter urging Gov. Jerry Brown to impose a moratorium on hydraulic fracturing to obtain oil and gas, the process commonly called “fracking.”

“The risks are simply too great to allow fracking to continue,” Assemblyman Marc Levine, who authored the letter, told reporters on a conference call this morning.

The technique demonstrably hurts air and water quality, might influence seismic activity, and furthers a dependence on fossil fuel that contributes to climate change, said Levine, D-San Rafael, and so it must be suspended “until we have all the data to address the immediate and long-term dangers.”

Levine, who announced the letter in November, teamed up with CREDO, an activist group which had thousands of members sign petitions and make phone calls urging their lawmakers to sign the letter. Levine and CREDO delivered the letter and held their news conference during this final week of a public comment period on Brown’s proposed fracking regulations, which they say would allow a massive expansion of fracking in California.

CREDO campaign manager Zack Malitz called fracking “one of the greatest environmental struggles to face Califonians in a generation,” and said Brown has proposed “dangerously weak regulations that would only encourage more fracking” despite “massive public opposition.”

“His legacy as an environmental leader is on the line,” Malitz said. “Californians will hold him responsible for putting oil-industry profits ahead of our health and the climate.”

Several bills proposing a moratorium on fracking failed to get enough votes to advance in the Legislature last year. The Legislature did pass SB 4 by state Sen. Fran Pavley, D-Calabassas, which Brown signed into law in September; that bill requires oil companies to go through a permit process, disclose chemical uses, do groundwater tests and send notices to neighboring landowners about their intent to drill.

Brown generally has pursued energy policy that supports increased oil production while expanding California’s goal of producing at least a third of its electricity from renewable sources (such as wind or solar energy) by 2020.

UPDATE @ 12:32 P.M.: This just in from Evan Westrup, Brown’s spokesman: “After extensive debate, the Legislature – including the authors of this letter – voted to enact SB 4, which became effective just days ago. Pursuant to this bill, the regulatory process has begun and we encourage these legislators and other interested citizens to actively participate.”